Grammatus labyrinthinus H.S. Yuan & C. Decock

Yuan, Hai-Sheng, Lu, Xu & Decock, Cony, 2018, Molecular and morphological evidence reveal a new genus and species in Auriculariales from tropical China, MycoKeys 35, pp. 27-39 : 31-33

Grammatus labyrinthinus H.S. Yuan & C. Decock sp. nov. Figures 3, 4

Diagnoses.

Basidiocarps annual, resupinate; hymenium restricted to the base of the tubes. Hymenophoral surface irregularly irpicoid to subporoid, then labyrinthine to sinuous. Subiculum very thin. Tubes shallow. Hyphal system dimitic; generative hyphae bearing clamp connections; skeletal hyphae IKI–, CB+. Skeletocystidia clavate, the upper part heavily encrusted. Dendrohyphidia present, thin- to slightly thick-walled. Basidia subglobose, longitudinally septate. Basidiospores oblong-ellipsoid to cylindrical, hyaline, thin-walled, smooth, IKI–, CB–.

Type.

China. Yunnan Province, Xishuangbanna, Jinghong County, Nabanhe Nat. Res., fallen angiosperm branch, 17.VIII.2005 Yuan 1759 (holotype: IFP 019121).

Etymology.

labyrinthinus (Lat.): refers to labyrinthine hymenophore.

Basidiocarps annual, resupinate, coriaceous, without special odour or taste when fresh, corky when dry, up to 15 cm long, 3 cm wide and 0.2 mm thick. Hymenophoral surface cream to pale buff when fresh, cinnamon-buff to yellowish-brown upon drying, firstly irregularly irpicoid to subporoid, the separate plates grow laterally and then develop into labyrinthine to sinuous pores, mostly 4-5 per mm, dissepiments thin; sterile margin up to 0.2 mm wide, pale yellow. Subiculum very thin (ca. 0.1 mm thick), cream to pale buff. Tubes corky, concolorous with pore surface, shallow, up to 130 µm deep, tube walls 120-200 µm thick. Hymenium restricted to the base of the tubes.

Hyphal structure. Hyphal system dimitic; generative hyphae bearing clamp connections, skeletal hyphae IKI–, CB+; tissue unchanged in KOH.

Subiculum. Dominated by skeletal hyphae; generative hyphae hyaline, thin-walled, rarely branched, 1.5-2.8 µm diam; skeletal hyphae hyaline, thick-walled to subsolid, straight to flexuous, covered by fine crystals, occasionally branched, interwoven, 1.8-3 µm diam.

Tubes. Generative hyphae infrequent, hyaline, thin-walled, rarely branched, 1.5-2.5 μm diam; skeletal hyphae dominant, hyaline, thick-walled to subsolid, moderately branched, interwoven, 1.8-2.8 μm diam. Skeletocystidia numerous, clavate, thick-walled, originating from and tightly embedded in trama, upper part heavily encrusted, 10-30 × 4-8 µm (with encrustation). Dendrohyphidia present, especially along the dissepiments, arising from generative hyphae, thin- to slightly thick-walled, apically moderately to strongly branched. Basidia subglobose, longitudinally septate, already septate as probasidia, 18-25 × 10-13 μm, epibasidia divided into four parts up to 20 μm long, bearing four sterigmata and without clamp connection at the base, sterigmata up to 20 μm long.

Basidiospores. Oblong-ellipsoid to cylindrical, hyaline, thin-walled, smooth, IKI–, CB–, (13 –)13.3–15.7(– 16) × (6 –)6.4–7.4(– 7.7) μm, L = 14.4 μm, W = 6.94 μm, Q = 2.07-2.1 (n = 60/2).

Type of rot.

White rot.

Additional specimens examined - China. Yunnan Province, Xishuangbanna, Jinghong County, Elephant Valley Forest Park, fallen angiosperm branch, 14.VIII.2005 Yuan 1600 (IFP 019118); Nabanhe Nat. Res., fallen angiosperm branch, 15.VIII.2005 Yuan 1683 (IFP 019119); fallen angiosperm branch, 17.VIII.2005 Yuan 1734 (IFP 019120).